Process of producing titanium dioxide



Patented Apr. 27, 1937 UNITED STATES PATENT OFFICE PROCESS OF PRODUCINGTITANIUM DIOXIDE poration of Ohio No Drawing.

Application June 30, 1933, Serial 9 Claims.

This invention relates to the addition of a titanate to titanium dioxidebefore calcination and has for its object the production of a titaniumdioxide of lower oil absorption, higher opaclty and better mixingqualities than the titanium dioxide now available.

I am aware that in the production of titanium dioxide a reagentinfluences the physical characteristics of the titanium dioxide duringcalcination. Apparently it does not matter at which stage the reagent isadded, as long as it is present during the calcination.

U. S. Patent 1,189,229, page 3, lines 9'7 to 99 inclusive, describes amixture of T102 and CaSO4.

U. S. Patent 1,171,542, page 3, lines 11 to 16 inclusive, gives theanalysis of a titanium oxide mixture before calcination, as follows:

Titanic oxide to Silica "I 1% to 5% Iron oxide 1% to 7% Sodium oxide 2%to 15% Sulfur, free 1% to 15% Sulphuric anhydride 0.1% to 1% I am alsoaware that it has been customary in industrial practice, to add theequivalent of 0.1% to 5% sodium oxide or potassium oxide in the form ofsodium or potassium carbonate, to the titanium dioxide content of theproduct being calcined.

I do not claim any of the above as my invention. I have discovered thata titanium dioxide having lower oil absorption, higher opacity andbetter mixing qualities than titanium dioxide now produced can beobtained by adding to titanium dioxide, which has been freed of all butapproximately one hundredth of one percent of water soluble salts, atitanate which will remain white or light colored after calcination inan amount equivalent to from one-tenth of one percent to two andone-half percent of the titanium dioxide; thoroughly mixing the titanateand titanium dioxide, calcining the mixture, grinding the calcinedproduct in a ball mill and drying.

In practicing my invention I boil a solution of titanium sulphate untila precipitate of titanium dioxide is formed; I thoroughly wash thisprecipitate with water until the wash water shows the absence of anywater soluble salts in quantities higher than approximately onehundredth of one percent. I then reslurry the titanium dioxide in water,adjusting the slurry to about 250 grams of T102 per liter; to thismixture I add from .25 to 6.25 grams of barium, strontium, calcium orother titanate of the alkali earth group which will remain white orlight colored upon calcination. I filter the slurry dry and calcine. Thetemperature of calcination depends upon the amount of titanate, thesmaller the quantity of titanate used, the higher the temperaturerequired for proper calcination. I have found that when using only onetenth of one percent of titanate the temperature of calcination shouldbe close to 1000 C. and when using 2.5% a temperature as low as 750 C,is sufficiently high.

Now having fully described my invention, I claim:

1. An improvement in the process of producing titanium dioxide whichconsists of washing a crude titanium dioxide precipitate until all butapproximately one hundredth of one percent of soluble salts have beenremoved, thoroughly mixing with said titanium dioxide a titanate of thealkali earth group which will remain white or light colored aftercalcination, in an amount equivalent to from one tenth of one percent totwo and one-half percent of said titanium dioxide and calcining.

2. An improvement in the process of producing titanium dioxide whichconsists of washing a crude titanium dioxide precipitate until all butapproximately one hundredth of one percent of soluble salts have beenremoved, thoroughly mixing with said titanium dioxide titanate of bariumin an amount equivalent to from one tenth of one percent to two andone-half percent of said titanium dioxide and calcining.

3. An improvement in the process of producing titanium dioxide whichconsists of washing a crude titanium dioxide precipitate until all butapproximately one hundredth of one percent of 35 soluble salts have beenremoved, thoroughly mixing with said titanium dioxide titanate ofcalcium in an amount equivalent to from one tenth of one percent to twoand one-half percent of said titanium dioxide and. calcining. 40

4. An improvement in the process of producing titanium dioxide whichconsists of washing a crude titanium dioxide precipitate until all butapproximately one hundredth of one percent of soluble salts have beenremoved, thoroughly mix- 45 ing with said titanium dioxide titanate ofstrontium in an amount equivalent to from one tenth of one percent totwo and one-half percent of said titanium dioxide and calcining.

5. A pigment consisting of titanium dioxide, and 0.1-2.5% alkali earthtitanate, intimately admixed and calcined together.

6. The process of producing pigment titanium dioxide from crude titaniumdioxide which comprises calcining the crude oxide with from 0.1 to

2.5% of an alkali earth titanate, in the absence of other dilutingpigments.

7. The process of producing pigment titanium dioxide from crude titaniumdioxide which com- 5 prises calcining the crude oxide with from 0.1 to2.5% of barium titanate in the absence of other diluting pigments.

8. The process of producing pigment titanium dioxide from crude titaniumdioxide which comprises calcining the crude oxide with from 0.1 to 2.5%of calcium titanate in the absence of other diluting pigments.

9. The process of producing pigment titanium dioxide from crude titaniumdioxide which comprises calcining the crude oxide with from 0.1 to 2.5%of strontium titanate in the absence of other diluting pigments.

HERBERT L. RHODES.

